The need to generate precise time delays is a requirement in many electronic applications. For this purpose, capacitor-based circuits are customarily used to generate time delays. Examples of such circuits are described in the article by W. F. Davis and T. M. Frederiksen entitled a precision monolithic time-delay generator for use in automotive electronic fuel injection systems, IEEE journal on solid state circuits, Vol. 7, No. 6, December 1972.
One of the drawbacks of this type of circuit is their footprint, notably when they are incorporated into an integrated circuit. Another drawback is that they cannot generate a wide range of time delays, for example with values ranging from one millisecond to several hundred minutes. Furthermore, if a capacitor-based delay generator is used, it is difficult to generate long delays, of about one hundred seconds for example, with precision.